Exercise for people with SCI can enhance physical fitness and slow secondary complications of SCI. Unfortunately, available exercise equipment is expensive and provides marginal benefits. In this Phase II project, we will continue to develop and evaluate an exercise system for individuals with SCI seeking to improve their physical fitness and/or enable use of a functional electrical stimulation system for standing. The device uses electrical stimulation of lower-extremity musculature to generate a coupled hip/knee bending motion that moves the upper body against gravity. It provides the ability to perform strength and endurance training exercises in a manner that provides graded loading of the lower extremities. It consists of mechanical frame and a multi-channel stimulator with an adaptive controller to generate the desired movement and GRF profiles. The Phase I project demonstrated feasibility by developing a prototype, evaluating it in experiments on human subjects with SCl, and identifying its limitations.The Phase II goals are to move towards Phase Ill commercialization by:1. Designing and developing an improved device; 2. Evaluating the ability to provide substantial exercise benefits in a clinical setting; 3. Characterizing the biomechanics of the exercise; and 4. Interfacing the device with an implanted electrical stimulation system. 3. characterizing the biomechanics of the exercise; and 4. interfacing the device with an implanted electrical stimulation system.